From ed679278030dda12b682033185ccaa1ecb170495 Mon Sep 17 00:00:00 2001
From: Sergiu Ivanov <sivanov@colimite.fr>
Date: Wed, 29 Mar 2023 01:21:29 +0200
Subject: [PATCH] Type make-tbf/state.

---
 scribblings/tbn.scrbl | 11 +++++++++++
 tbn.rkt               | 11 ++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/scribblings/tbn.scrbl b/scribblings/tbn.scrbl
index 539579f..044e0da 100644
--- a/scribblings/tbn.scrbl
+++ b/scribblings/tbn.scrbl
@@ -70,3 +70,14 @@ Shorter synonyms for field accessors of @racket[tbf/state].
   (values (tbf/state-w tbfs)
           (tbf/state-θ tbfs)))
 ]}
+
+@defproc[(make-tbf/state [pairs (Listof (Pairof Variable Real))]
+			 [threshold Real])
+			 TBF/State]{
+
+Makes a @racket[TBF/State] from a list of pairs of names of variables
+and weights, as well as a threshold.
+
+@ex[
+(make-tbf/state '((x1 . 1) (x2 . 1)) 1)
+]}
diff --git a/tbn.rkt b/tbn.rkt
index 34f9625..116f805 100644
--- a/tbn.rkt
+++ b/tbn.rkt
@@ -15,7 +15,7 @@
   (provide
    apply-tbf-to-state
 
-   (struct-out tbf/state) TBF/State tbf/state-w tbf/state-θ
+   (struct-out tbf/state) TBF/State tbf/state-w tbf/state-θ make-tbf/state
    )
 
   (: apply-tbf-to-state (-> TBF (State (U Zero One)) (U Zero One)))
@@ -36,6 +36,15 @@
   (define tbf/state-w tbf/state-weights)
   (define tbf/state-θ tbf/state-threshold)
 
+  (: make-tbf/state (-> (Listof (Pairof Variable Real)) Real TBF/State))
+  (define (make-tbf/state pairs threshold)
+    (tbf/state (make-immutable-hash pairs) threshold))
+
+  (module+ test
+    (test-case "tbf/state"
+      (define f (make-tbf/state '((x1 . 1) (x2 . 1)) 1))
+      (check-equal? (tbf/state-w f) #hash((x1 . 1) (x2 . 1)))
+      (check-equal? (tbf/state-θ f) 1)))
   )
 
 (module+ test